In general, a vehicle is equipped with various lamp devices, such as a headlamp for illuminating the area ahead of the vehicle, a turn signal lamp for indicating a change in the traveling direction of the vehicle, a fog lamp for indicating the position of the vehicle in fog, a brake lamp for indicating a braking action of the vehicle, a rear lamp for illuminating the area behind the vehicle when the vehicle travels backwards, and a tail lamp for indicating the overall width of the vehicle to drivers behind the vehicle.
A lamp for a vehicle typically includes a light source for emitting light, a reflector for reflecting the light emitted from the light source in a forward direction, and a lens for refracting the light reflected by the reflector and forming a light distribution pattern.
A bulb or a light-emitting diode (LED) is often used as the light source for a vehicle lamp. The light emitted from the bulb or the LED is typically reflected forward by the reflector and is refracted while passing through the lens, thereby forming a desired light distribution pattern.